About this book

This experiment shows children how the acid from the germs in their mouth can dissolve the calcium in their teeth and weaken them.

You will need: white vinegar, plain water, two pieces of eggshell, two cups

Put one piece of eggshell in a cup.

Cover this eggshell with a few tablespoons of vinegar.

Put the other piece of eggshell in the second cup.

Cover this piece with a few tablespoons of plain water.

Soak the shells for a few days. Then have children feel them. Ask: Which one is still hard? Which one is soft and weak?

Put the soft eggshell back in the cup with the vinegar. Leave it until all the vinegar evaporates. Then have children look at it. Ask: Is there a white powder at the bottom of the cup? What do you think this is? [The white powder is calcium. The calcium was removed from the eggshell (the teeth) by the vinegar (the tooth-germ acid).]